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><H1
><A
NAME="SQL-ALTERFOREIGNTABLE"
></A
>ALTER FOREIGN TABLE</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN60322"
></A
><H2
>Name</H2
>ALTER FOREIGN TABLE&nbsp;--&nbsp;change the definition of a foreign table</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN60327"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>ALTER FOREIGN TABLE <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>
    <TT
CLASS="REPLACEABLE"
><I
>action</I
></TT
> [, ... ]
ALTER FOREIGN TABLE <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>
    RENAME [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column</I
></TT
> TO <TT
CLASS="REPLACEABLE"
><I
>new_column</I
></TT
>
ALTER FOREIGN TABLE <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>
    RENAME TO <TT
CLASS="REPLACEABLE"
><I
>new_name</I
></TT
>
ALTER FOREIGN TABLE <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>
    SET SCHEMA <TT
CLASS="REPLACEABLE"
><I
>new_schema</I
></TT
>

<SPAN
CLASS="phrase"
><SPAN
CLASS="PHRASE"
>where <TT
CLASS="REPLACEABLE"
><I
>action</I
></TT
> is one of:</SPAN
></SPAN
>

    ADD [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column</I
></TT
> <TT
CLASS="REPLACEABLE"
><I
>type</I
></TT
> [ NULL | NOT NULL ]
    DROP [ COLUMN ] [ IF EXISTS ] <TT
CLASS="REPLACEABLE"
><I
>column</I
></TT
> [ RESTRICT | CASCADE ]
    ALTER [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column</I
></TT
> [ SET DATA ] TYPE <TT
CLASS="REPLACEABLE"
><I
>type</I
></TT
>
    ALTER [ COLUMN ] <TT
CLASS="REPLACEABLE"
><I
>column</I
></TT
> { SET | DROP } NOT NULL
    OWNER TO <TT
CLASS="REPLACEABLE"
><I
>new_owner</I
></TT
>
    OPTIONS ( [ ADD | SET | DROP ] <TT
CLASS="REPLACEABLE"
><I
>option</I
></TT
> ['<TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
>'] [, ... ])</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN60349"
></A
><H2
>Description</H2
><P
>   <TT
CLASS="COMMAND"
>ALTER FOREIGN TABLE</TT
> changes the definition of an
   existing foreign table.  There are several subforms:

  <P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>ADD COLUMN</TT
></DT
><DD
><P
>      This form adds a new column to the foreign table, using the same syntax as
      <A
HREF="sql-createforeigntable.html"
>CREATE FOREIGN TABLE</A
>.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>DROP COLUMN [ IF EXISTS ]</TT
></DT
><DD
><P
>      This form drops a column from a foreign table.
      You will need to say <TT
CLASS="LITERAL"
>CASCADE</TT
> if
      anything outside the table depends on the column; for example,
      views.
      If <TT
CLASS="LITERAL"
>IF EXISTS</TT
> is specified and the column
      does not exist, no error is thrown. In this case a notice
      is issued instead.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>SET DATA TYPE</TT
></DT
><DD
><P
>      This form changes the type of a column of a foreign table.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>SET</TT
>/<TT
CLASS="LITERAL"
>DROP NOT NULL</TT
></DT
><DD
><P
>      Mark a column as allowing, or not allowing, null values.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>OWNER</TT
></DT
><DD
><P
>      This form changes the owner of the foreign table to the
      specified user.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>RENAME</TT
></DT
><DD
><P
>      The <TT
CLASS="LITERAL"
>RENAME</TT
> forms change the name of a foreign table
      or the name of an individual column in a foreign table.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>SET SCHEMA</TT
></DT
><DD
><P
>      This form moves the foreign table into another schema.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>OPTIONS ( [ ADD | SET | DROP ] <TT
CLASS="REPLACEABLE"
><I
>option</I
></TT
> ['<TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
>'] [, ... ] )</TT
></DT
><DD
><P
>      Change options for the foreign table.
      <TT
CLASS="LITERAL"
>ADD</TT
>, <TT
CLASS="LITERAL"
>SET</TT
>, and <TT
CLASS="LITERAL"
>DROP</TT
>
      specify the action to be performed.  <TT
CLASS="LITERAL"
>ADD</TT
> is assumed
      if no operation is explicitly specified.  Option names must be
      unique; names and values are also validated using the foreign
      data wrapper library.
     </P
></DD
></DL
></DIV
><P>
  </P
><P
>   All the actions except <TT
CLASS="LITERAL"
>RENAME</TT
> and <TT
CLASS="LITERAL"
>SET SCHEMA</TT
>
   can be combined into
   a list of multiple alterations to apply in parallel.  For example, it
   is possible to add several columns and/or alter the type of several
   columns in a single command.
  </P
><P
>   You must own the table to use <TT
CLASS="COMMAND"
>ALTER FOREIGN TABLE</TT
>.
   To change the schema of a foreign table, you must also have
   <TT
CLASS="LITERAL"
>CREATE</TT
> privilege on the new schema.
   To alter the owner, you must also be a direct or indirect member of the new
   owning role, and that role must have <TT
CLASS="LITERAL"
>CREATE</TT
> privilege on
   the table's schema.  (These restrictions enforce that altering the owner
   doesn't do anything you couldn't do by dropping and recreating the table.
   However, a superuser can alter ownership of any table anyway.)
  </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN60412"
></A
><H2
>Parameters</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
></DT
><DD
><P
>        The name (possibly schema-qualified) of an existing foreign table to
        alter.
       </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>column</I
></TT
></DT
><DD
><P
>        Name of a new or existing column.
       </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>new_column</I
></TT
></DT
><DD
><P
>        New name for an existing column.
       </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>new_name</I
></TT
></DT
><DD
><P
>        New name for the table.
       </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>type</I
></TT
></DT
><DD
><P
>        Data type of the new column, or new data type for an existing
        column.
       </P
></DD
><DT
><TT
CLASS="LITERAL"
>CASCADE</TT
></DT
><DD
><P
>        Automatically drop objects that depend on the dropped column
        (for example, views referencing the column).
       </P
></DD
><DT
><TT
CLASS="LITERAL"
>RESTRICT</TT
></DT
><DD
><P
>        Refuse to drop the column if there are any dependent
        objects. This is the default behavior.
       </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>new_owner</I
></TT
></DT
><DD
><P
>        The user name of the new owner of the table.
       </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>new_schema</I
></TT
></DT
><DD
><P
>        The name of the schema to which the table will be moved.
       </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN60460"
></A
><H2
>Notes</H2
><P
>    The key word <TT
CLASS="LITERAL"
>COLUMN</TT
> is noise and can be omitted.
   </P
><P
>    Consistency with the foreign server is not checked when a column is added
    or removed with <TT
CLASS="LITERAL"
>ADD COLUMN</TT
> or
    <TT
CLASS="LITERAL"
>DROP COLUMN</TT
>, a <TT
CLASS="LITERAL"
>NOT NULL</TT
> constraint is
    added, or a column type is changed with <TT
CLASS="LITERAL"
>SET DATA TYPE</TT
>.  It is
    the user's responsibility to ensure that the table definition matches the
    remote side.
   </P
><P
>    Refer to <A
HREF="sql-createforeigntable.html"
>CREATE FOREIGN TABLE</A
> for a further description of valid
    parameters.
   </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN60471"
></A
><H2
>Examples</H2
><P
>   To mark a column as not-null:
</P><PRE
CLASS="PROGRAMLISTING"
>ALTER FOREIGN TABLE distributors ALTER COLUMN street SET NOT NULL;</PRE
><P>
  </P
><P
>   To change options of a foreign table:
</P><PRE
CLASS="PROGRAMLISTING"
>ALTER FOREIGN TABLE myschema.distributors OPTIONS (ADD opt1 'value', SET opt2, 'value2', DROP opt3 'value3');</PRE
><P></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN60477"
></A
><H2
>Compatibility</H2
><P
>   The forms <TT
CLASS="LITERAL"
>ADD</TT
>, <TT
CLASS="LITERAL"
>DROP</TT
>,
   and <TT
CLASS="LITERAL"
>SET DATA TYPE</TT
>
   conform with the SQL standard.  The other forms are
   <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> extensions of the SQL standard.
   Also, the ability to specify more than one manipulation in a single
   <TT
CLASS="COMMAND"
>ALTER FOREIGN TABLE</TT
> command is an extension.
  </P
><P
>   <TT
CLASS="COMMAND"
>ALTER FOREIGN TABLE DROP COLUMN</TT
> can be used to drop the only
   column of a foreign table, leaving a zero-column table.  This is an
   extension of SQL, which disallows zero-column foreign tables.
  </P
></DIV
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